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2026-05-12 errors csharp dotnet

Fix: System.IO.FileNotFoundException: Could not load file or assembly in a published app

Runs fine with dotnet run, throws after dotnet publish. The DLL is usually missing from the publish folder, not the runtime. Check deps.json, ProjectReference Private, and trimming.

2026-05-12 errors csharp dotnet

Fix: InvalidOperationException: Synchronous operations are disallowed

Replace the Stream.Read or Write call with ReadAsync/WriteAsync. As a last resort, set AllowSynchronousIO on Kestrel, IIS, or per-request via IHttpBodyControlFeature.

2026-05-12 errors csharp dotnet

Fix: RZ10012: Found markup element with unexpected name in Blazor

Blazor's Razor compiler emits RZ10012 when a PascalCase tag has no matching component type in scope. Add @using for the component's namespace in _Imports.razor, or @namespace in the component, then rebuild.

2026-05-12 llm ai-agents claude-code

How to Cache Multi-Turn Claude Conversations Across API Calls

Place rolling cache_control breakpoints across messages, respect the 20-block lookback, and refresh the 5-minute TTL automatically so a 50-turn agent loop pays the prefix once, not fifty times. Verified against anthropic 0.42 (Python) and @anthropic-ai/sdk 0.30 (Node) in May 2026.

2026-05-11 cursor ai-agents pull-requests

Cursor 3.3 Adds Build in Parallel, Split PRs, and a Unified PR Review

Cursor 3.3 (May 7, 2026) ships async subagents that work on independent steps of a plan at the same time, a quick action that splits one chat into multiple pull requests, and a redesigned PR workflow that keeps reviews, commits, and changes in one place.

2026-05-11 errors csharp dotnet

Fix: dotnet ef migrations add fails with 'Unable to create an object of type DbContext'

EF Core's design-time tools could not instantiate your DbContext. Either expose a host via WebApplication.CreateBuilder, point to the right startup project, or implement IDesignTimeDbContextFactory.

2026-05-11 errors csharp dotnet

Fix: MSB3027 Could not copy X to Y. Exceeded retry count of 10. Failed

MSB3027 means MSBuild retried a file copy 10 times and a process still held the destination. Kill the locking process, exclude bin/obj from antivirus, or raise CopyRetryCount.

2026-05-11 errors csharp dotnet

Fix: The type or namespace name 'X' could not be found (after adding a project reference)

CS0246 right after a fresh ProjectReference is almost always a TargetFramework mismatch, a stale obj folder, or a missing using directive. Five fixes in order of likelihood.

2026-05-11 ai-agents llm claude-code

How to Set Up an LLM-as-Judge Eval Harness for a Coding Agent

Build a working LLM-as-judge eval harness for a coding agent in Python: golden tasks, deterministic checks, a rubric judge on Claude Sonnet 4.6, calibration against human labels, and a CI gate that fails the build when scores regress.

2026-05-10 github-copilot ai-agents claude

GitHub Copilot Drops Claude Sonnet 4 From Every Surface

GitHub deprecated claude-sonnet-4 on May 6, 2026 across Copilot Chat, inline edits, ask and agent modes, and code completions. Recommended migration target is Claude Sonnet 4.6. What to grep for in your repo before the next pinned model selection silently breaks.